Narrated Zaynab daughter of Abu Salamah: Abu Salamah said: Zaynab daughter of Abu Salamah reported to me that a woman had a copious flow of blood. She was the wife of Abdur Rahman ibn Awf. The Messenger of Allah ﷺ commanded her to take a bath at the time of every prayer, and then to pray. He reported to me that Umm Bakr told him that Aishah said: The Messenger of Allah ﷺ said about a woman who was doubtful of her menstruation after purification that it was a vein or veins. Abu Dawud said: The two commands (of which the Prophet gave option) were as follows in the version reported by Ibn Aqil: He said: If you are strong enough, then take a bath for every prayer; otherwise combine the (two prayers), as al-Qasim reported in his version. This statement was also narrated by Saeed bin Jubair from Ali and Ibn Abbas.
Hadith Referenceسنن ابي داود / كتاب الطهارة / 293
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:ضعيف, إسناده ضعيف, يحيي بن أبي كثير مدلس (طبقات المدلسين: 63/ 2 وھو من الثالثة) وعنعن, وحديث أم بكر ضعيف لجھالة حالھا, ورواه ابن ماجه (646), انوار الصحيفه، صفحه نمبر 25
293. Commentary: Both narrations of Sunan Abi Dawud [292] and [293] are weak. Therefore, it is not necessary to perform a ritual bath (ghusl) for every prayer. After becoming pure from menstruation (hayd), a single ritual bath (ghusl) is sufficient. In Sunan Abi Dawud, in hadiths [290] and [291], the practice of Umm Habibah radi Allahu anha performing a ritual bath (ghusl) for every prayer has been mentioned. Regarding this, Imam Shafi'i rahimahullah states that Umm Habibah radi Allahu anha performed a ritual bath (ghusl) for every prayer out of her own preference; she was not commanded to do so. For details, see: [نيل الأوطار، باب غسل المستحاضة لكل صلاة، 1۔ 283۔ 284] However, Shaykh al-Albani rahimahullah and some other scholars have declared Sunan Abi Dawud hadith [292، 293] to be authentic. See: [صحيح سنن أبى داود، تعليقات السيل الحرار : 347/1، 348] A way to reconcile these views is that a single ritual bath (ghusl) is obligatory, but performing a ritual bath (ghusl) for every prayer is recommended (mustahabb). «والله أعلم»
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 293